in reply to Perl - calling javascript funciton

Have a look at JavaScript::DataFormValidator, it seems to be what you are looking for: a combination of client-side Javascript validation and server-side Perl validation.

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James